In a manufacturing environment, it is often necessary to transport articles of manufacture from one processing area to another. During transportation, some articles are particularly sensitive to contamination and electrostatic discharges, and thus these articles are often damaged.
For example, a particle deposited on an integrated circuit substrate can compromise the integrity of its integrated circuits. In addition, exposure of the integrated circuit substrate to moisture can cause its aluminum lines to corrode, or its photoresist patterns to swell or delaminate, while exposure to oxygen can cause unwanted oxidation of its exposed surfaces. Furthermore, an electrostatic discharge involving the integrated circuit substrate can render its integrated circuits inoperable. Similarly, the integrity of carbon coated disk drive media can be compromised by unwanted exposure to oxygen, which can cause the carbon coating to become oxidized, while the integrity of packaged integrated circuits can be compromised by moisture, which can cause package cracking.
One proposed method for protecting these sensitive articles during transportation is to place the articles within a first plastic bag and then to place the first plastic bag within a second plastic bag. The plastic bags, however, are often penetrated by gaseous contaminates from the external ambient, and thus the articles are contaminated. In addition, during the double bagging process itself, gaseous contaminates are trapped within the bags and the articles are contaminated. Furthermore, the plastic bags themselves often outgas contaminants and contaminate the articles.
Another proposed method is to place the articles within a first portable container, and then to pressurize the first portable container with nitrogen. As a safety precaution, the first portable container may be fitted with a pressure relief valve so that it is not accidentally over-pressurized. The first portable container may then placed within a second portable container, and the second portable container subsequently pressurized with nitrogen. As a safety precaution, the second portable container also may be fitted with a pressure relief valve so that it is not accidentally over-pressurized. The articles may then transported to their next destination via the first and second portable containers. During transportation a nitrogen cylinder mounted to the second portable container may be used to ensure that a positive pressure is maintained within the second portable container. The positive nitrogen pressure within the first container and the second container may inhibit penetration of the containers by gaseous contaminates from the external ambient. Such a double container process, however, does not fully prevent gaseous contaminates from being trapped within the containers, and thus allows the articles to be contaminated. In addition, the portable containers are often metal, and ungrounded. Therefore, articles placed within the containers are often damaged by electrostatic discharges, which occur between the articles and the metal container.
Accordingly, a need exists for an efficient way to transport and store sensitive articles, while at the same time minimizing damage due to contamination or electrostatic discharges.